RDMA/core: Check for error instead of success in alloc MR function

The common kernel pattern is to check for error, not success.  Flip the if
statement accordingly and keep the main flow unindented.

Link: https://lore.kernel.org/r/20200706120343.10816-2-galpress@amazon.com
Signed-off-by: Gal Pressman <galpress@amazon.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/verbs.c

@@ -2133,18 +2133,19 @@ struct ib_mr *ib_alloc_mr_user(struct ib_pd *pd, enum ib_mr_type mr_type,
 	}
 
 	mr = pd->device->ops.alloc_mr(pd, mr_type, max_num_sg, udata);
-	if (!IS_ERR(mr)) {
-		mr->device  = pd->device;
-		mr->pd      = pd;
-		mr->dm      = NULL;
-		mr->uobject = NULL;
-		atomic_inc(&pd->usecnt);
-		mr->need_inval = false;
-		mr->res.type = RDMA_RESTRACK_MR;
-		rdma_restrack_kadd(&mr->res);
-		mr->type = mr_type;
-		mr->sig_attrs = NULL;
-	}
+	if (IS_ERR(mr))
+		goto out;
+
+	mr->device = pd->device;
+	mr->pd = pd;
+	mr->dm = NULL;
+	mr->uobject = NULL;
+	atomic_inc(&pd->usecnt);
+	mr->need_inval = false;
+	mr->res.type = RDMA_RESTRACK_MR;
+	rdma_restrack_kadd(&mr->res);
+	mr->type = mr_type;
+	mr->sig_attrs = NULL;
 
 out:
 	trace_mr_alloc(pd, mr_type, max_num_sg, mr);